Ash Silica Research Articles

1-18.石炭灰の軟化点と単体シリカ変態点との相関(Session(1)石炭利用)

1-18.石炭灰の軟化点と単体シリカ変態点との相関(Session(1)石炭利用)

Adaptation of eco-friendly approach in the production of soluble pozzolanic material

Silica gel made of natural waste materials of sugarcane bagasse has initiated a new trend in pozzolanic area. The employment of eco-friendly approach by using low concentration acids and natural drying via solar heat based equipment in the pre-treatment process were projected to minimize the energy consumption in producing silica ash. Conversion of ultrafine silica ash from sugarcane bagasse into silica gel was conducted by-using a modified hydrothermal method. NaOH and HCI solution were employed in the dissolution and gelification of soluble silica. Analysis on the effect of silica gel in cementitious system was evaluated by including it in mortar specimen as a pozzolan to replace certain portion of Portland cement. Inclusion of additional siliceous gel showed enhancement in the cement hydration process, which resulted in early hardening and consolidatedformation of cement matrix to further contribute in the strength development. Measurement of pozzolanic reactivity of silica gel via Chapelle method verified the active consumption of Ca(OH)2 by the soluble silica, which illustrates the possible formation of secondary calcium silicate hydrate (C-S-H) from the pozzolanic reaction. Densification of pore structure via large voids were observed via porosity test at age of 7 and 28 days. Based on the experimental result in this study, silica gel has presented an encouraging prospect to be used as a cement replacement material. Its rapid reaction during the early age would be beneficial in providing early strength properties to the cement based product.

High-Strength Solidification of Fly Ash/Carbide Slag and Its Fixing Ability for Heavy Metals

Hydrothermal hot-pressing will occur between silica in fly ash and calcium in carbide slag and give rise to high-strength hydrates. High-strength solidified specimens were prepared with fly ash and carbide slag via hydrothermal hot-pressing at 200°C and 7 MPa. The effect of concentration of activator and content of carbide slag on compressive strength of the specimens was analyzed. It was found that when the mass ratio of fly ash to carbide slag was 1:1 and 20% 5 mol/L NaOH solution was added, the solidified specimens contained a large amount of cross-linked fibrous tobermorite with compressive strength of 70.93 MPa. The solidified specimens had a good fixation effect on such heavy metals as Cu, Zn, Cd and Pb. Hydrothermal hot-pressing, featured by simple procedures, easy automation and low cost, is an ideal potential way of utilizing fly ash and carbide slag and fixation of heavy metals.

Studies on the Synthesis of Silica Powder from Rice Husk Ash as Reinforcement Filler in Rubber Tire Tread Part: Replacement of Commercial Precipitated Silica

Rice husks, which can be considered as an agricultural waste, are produced every year in South Gonder, Ethiopia. Precipitated silica is commonly used as reinforcing filler in rubber industry, in the present study an effort has been attempted to replace commercial silica commonly used in natural rubber industries with rice husk ash silica (RHAS). Silica was extracted from RHA by using alkaline extraction followed by acid precipitation. The synthesized RHAS was characterized by AAS, BET, DSC, FTIR, and XRD. RHAS was then used as reinforcing filler in natural rubber. The curing characteristics of natural rubber products filled with RHAS resulted a smaller scorch time which caused a premature vulcanization than the commercial silica filled rubber composite. Overall mechanical properties like hardness, young’s modulus, abrasion resistance of rubber products reinforced with RHAS was better than commercial silica filled rubber composite.

Pediastrum boryanum Immobilized on Rice Husk Ash Silica as Biosorbent for Fluoride Removal from Drinking Water

Objectives: Biosorption is an environmentally friendly approach for the removal of organic and inorganic compounds from aqueous solutions. Fluoride concentration in drinking water above 1.5 mg∙L-1 is harmful to human health. The aim of this study was to develop analgae immobilization method using silica gel extracted from renewable rice husk ash and test the biosorbent in defluoridation of water. Methods: Pediastrumboryanum was immobilized using sodium silicate extracted from rice husk ash. The method involved suspending the biomass in a sodium silicate rich filtrate prepared through alkaline leaching of rice husk ash. The immobilization was achieved through acid precipitation of silica. The biosorbent was used in the defluoridation of water and had improved mechanical properties. Findings: The maximum adsorption capacity was 25.641 mg∙g-1 at pH 5. Experimental data fitted well into the Langmuir adsorption isotherm (R2 = 0.9987) although Freundlich adsorption isotherm (R2=0.9898) could also be used to describe biosorption processes. The biosorption process was of the pseudo-second order kinetics with R2 ≥ 0.9988. FT-IR spectra revealed the presence of –OH, -NH, C-O-C and –C=O functional groups. Application: This study demonstrate the feasibility to immobilize Pediastrumboryanum using sodium silicate extracted from renewable bio-waste instead of using commercially available sodium silicate. Experimental results present the possibility to application of the biosorbent in the defluoridation of water.

Analisa Daya Serap Silika Gel Berbahan Dasar Abu SekamPadi

Rice husk ash Silica Gel is aproduct which call be used in preventing the humidity by absorbing the water ion on the water andonthe air. This absorbing isbased onthe size, the composition and the total amount ofpolluter which contained on the Silica Gel. The purpose of making this silica gel is to seehow much thiskind of Silica Gel can absorb and compare it to the synthetic one,and also processing rise husk ashto be something useful, Ion water can be absorbed much more by using this natural silica gel if it is compared to the synthetic silica gel. This is because of its capable inabsorbing more –OHand O from water and air. Afterdoing a research with column method, silica gel was beingput in 50 ml water. Fromthis research, natural silica can absorb much more water (0.0010 gr/ml), 0.285 % water level ofweigh in comparing with synthetic one (0.008gr/ml) with 0.248 %water level ofweight andsintering (0,007 gr/ml) 0.253%water level and non-sintering silica gel contains 39.22 % weight of silica, 30.93 %weight of sintering silica gel, and 33.40 % of the synthetic. More silica and water level, means more total amount of absorbing. This silica gel application is considered with capability ofabsorbing andthe level of the water.

Silicon Release from Local Materials in Indonesia under Submerged Condition

Five inorganic materials (steel slag, silica gel, electric furnace slag, fly ash and Japanese silica fertilizer) and six organic materials (rice husk-biochar, rice straw compost, media of mushroom, cacao shell-biochar, rice husk-ash and elephant grass), were evaluated as Si fertilizer sources for rice plants (Oryza sativa L.) in two soil types (red clayey and sandy soil). Evaluation was carried out by incubating them at 30oC under submerged condition for 70 days. The soil solution was replaced at day 7, 14, 21, 42, 49, 56, 63 and 70 and the amount of silicon (Si) release, pH, Eh, calcium (Ca), magnesium (Mg), iron (Fe) and manganese (Mn) concentrations in soil solutions were determined. The amount of Si release ranged from n.d. (not detected)-32444.7 mg Si kg-1 and 105.84-48524.0 mg Si kg-1 in red clayey and sandy soil solutions, respectively during 70 days of incubation. Reduction in soil Eh was accompanied with an increase in the solubility of the soil Si especially for silica gel, electric furnace slag, elephant grass and media of mushroom. Higher exchangeable Ca content in soil tended to suppress Si release from rice straw compost, rice husk-ash and cacao shell-biochar. Considering the results of present study and availability of the materials, we concluded that steel slag of the inorganic materials and rice straw/husk and cacao shell-biochar of organic materials had the highest potential as Si fertilizer source in Indonesia.

Comparison between Rice Husk Ash and Commercial Silica as Filler in Polymeric Composites

The use of rice husk ash (RHA) as filler in polymeric materials has been studied in different polymers. Research reported that RHA may successfully replace silica. The silica production process using ore demands high energy input and produces considerable amounts of waste. Therefore, the replacement of silica by RHA may be economically and environmentally advantageous, reducing environmental impact and adding value to a waste material. In this context, this study characterizes and compares RHA of different sources (moving grate and fluidized bed reactor) with commercially available silicas to assess performance as filler in polymeric materials. Samples were characterized by X-ray fluorescence, loss on ignition, X-ray diffraction, grain size, specific surface area, specific weight, and scanning electron microscopy. The results show that RHA may be used as a filler in several polymeric materials.

Catalytic upgrading of Elephant grass (Pennisetum purpureum Schum) pyrolysis vapor using WO3 supported on RHA and RHA-MCM-41

Recently, zeolites have been widely applied in catalytic pyrolysis to improve physical and chemical properties of bio-oil to produce energy or to selectively produce chemicals for industry. This study aims to analyze the catalytic pyrolysis products of Elephant Grass (EG) using WO3 catalysts supported on rice husk ash (RHA) silica and RHA-MCM-41, being low cost materials derived from agro industrial waste, and evaluate the catalysts activity in the formation of deoxygenated compounds. Elephant Grass has been shown as a potential energy crop that has fast growth and is easy to cultivate in different countries, including Brazil. Its energetic characterization was evaluated by proximate and ultimate analysis, High Heat Value (HHV), cellulose, hemicellulose and lignin content, chemical ash composition by FRX and bulk density. Pyrolysis analysis was performed at 500°C in a Py-5200 HP-R connected to a GC–MS, and pyrolysis vapors were carried by N2 to a catalytic bed at 400 and 600°C. It was noticed that increasing catalyst temperature promotes cracking reactions leading to increased aromatic content. The main oxygenated pyrolysis products of EG such as phenols, furans, ketones and acetic acid were converted at 600°C using WO3/RHA catalyst into aromatics (benzene, toluene, xylene, styrene), being of high added value for chemical industry. The main influence on aromatics yields could be related to catalytic activity of WO3 promoted by its redox ability and the rise in temperature which favors cracking reactions.

Computational Investigation of the Influence of Fly Ash Silica Content and Shape on the Erosion Behaviour of Indian Coal Fired Boiler Grade Steels

A mathematical model has been developed to characterize the erosion behaviour of fly ash on boiler grade steel surfaces incorporating various ductile erosion mechanisms. These mechanisms constitute cutting wear, repeated plastic deformation and effect of operating temperature on the mechanical properties of the substrate. Parametric analysis has been carried out to study the erosion response of some typical steel grades as a function of particle impact parameters such as particle impact velocity, angle of impingement coupled with the effect of temperature on the tensile properties. Further, effects of fly ash properties such as hardness (silica content) and shape (angularity) on the erosion response have been also investigated along with the ballistic parameters. These investigations show that a small increment in the fly ash hardness can considerably augment the erosion rate of the steel surface under a given particle impingement condition. This vindicates that hardness of fly ash is one of the most critical parameter which has a direct impact in enhancing the erosion rate of boiler grade steels. The effect of fly ash shape on the erosion behaviour is also studied in conjunction with the particle hardness. This shows that the composite action of these parameters augment the erosion rate significantly.

Fabrication and characterization of strontium incorporated 3-D bioactive glass scaffolds for bone tissue from biosilica

Bioactive glass scaffolds that contain silica are high viable biomaterials as bone supporters for bone tissue engineering due to their bioactive behaviour in simulated body fluid (SBF). In the human body, these materials help inorganic bone structure formation due to a combination of the particular ratio of elements such as silicon (Si), calcium (Ca), sodium (Na) and phosphorus (P), and the doping of strontium (Sr) into the scaffold structure increases their bioactive behaviour. In this study, bioactive glass scaffolds were produced by using rice hull ash (RHA) silica and commercial silica based bioactive glasses. The structural properties of scaffolds such as pore size, porosity and also the bioactive behaviour were investigated. The results showed that undoped and Sr-doped RHA silica-based bioactive glass scaffolds have better bioactivity than that of commercial silica based bioactive glass scaffolds. Moreover, undoped and Sr-doped RHA silica-based bioactive glass scaffolds will be able to be used instead of undoped and Sr-doped commercial silica based bioactive glass scaffolds for bone regeneration applications. Scaffolds that are produced from undoped or Sr-doped RHA silica have high potential to form new bone for bone defects in tissue engineering.

The effect of curing on the properties of metakaolin and fly ash-based geopolymer paste

Abstract Fly ash was used as the raw material in the preparation of geopolymer paste and metakaolin was used as a substitution material in different ratios. Metakaolin material was made of kaolin clay calcined at a temperature of 1000 °C and at a final temperature for 1 h in a laboratory-type electric arc furnace. The fly ash in the prepared mixture was substituted by metakaolin ranging from 10% to 40%. In the mixtures, NaOH was used as the reactive together with a 3-module sodium silicate solution to solve silica and alumina in the fly ash and metakaolin particles. A 9 M NaOH solution was used in the preparation of the geopolymer pastes and the liquid/solid ratio used in the mixtures was 0.36 ml/gr. The pastes were cast into a 25 by 50-mm cylinder mold. This process was performed under a 100 bar pressure using a hydraulic hand press. Afterwards, the samples were placed in a laboratory-type oven for thermal curing. The samples were subjected to curing at 60 °C and 80 °C (two different curing temperatures) for 2 h, 4 h and 24 h (three different curing times). Following curing, the samples were maintained under laboratory conditions at room temperature until the day of the physical and mechanical tests. 7-day geopolymer paste samples were used for the tests. As a result, the ideal curing temperature and curing time were decided to be 60 °C and 2 h for the production of the geopolymer paste. It was also determined that the compressive strength values of the samples subjected to curing reached up to 25.1 MPa and that a 40% metakaolin substitution provided a better geopolymerization and significantly improved compressive strength values.

Preparation and Characterization of Active SiO2 from Cymbopogon citratus Ash Calcined at Different Temperature

Cymbopogon citratus or lemon grass, is a potential renewable herbaceous biomass alternative. Lemon grass contains silica, which is available for extraction as a filler for various applications. Lemon grass ash is produced at calcination temperatures of 0, 400, 525, 600, and 700 ˚C. The silica content of the lemon grass ash was characterized by X-ray fluorescence (XRF), X-ray powder diffraction (XRD), scanning electron microcopy (SEM), and Fourier transform infrared (FTIR) analysis. The shape and texture of the lemon grass ash were studied by SEM. The highest silica content recorded was 24.00% for lemon grass calcined at 400 °C. The porosity of the lemon grass ash increased as the calcination temperature increased from 0 °C to 700 °C. XRD analysis showed that the crystallinity of silica in the lemon grass ash increased with increasing calcination temperature. FTIR analysis confirmed the presence of organic structure in lemon grass without calcination and the inorganic structure of siloxane and silanol bonds present in lemon grass calcined at different temperatures.

Case Study: Technical Considerations to Optimize Rice Husk Burning in a Boiler to Retain a High Solubility of the Silica in Rice Husk Ash

Case Study: Technical Considerations to Optimize Rice Husk Burning in a Boiler to Retain a High Solubility of the Silica in Rice Husk Ash

A Proposal for Measuring Solubility of the Silica in Rice Husk Ash

A Proposal for Measuring Solubility of the Silica in Rice Husk Ash

Mechanical Properties of Friction Stir Processed 1100 Aluminum Reinforced with Rice Husk Ash Silica at Different Rotational Speeds

This paper presents a study on friction stir processed 1100 aluminum withincorporation of rice huskash derived, amorphous silica particles and fabricated at different tool rotational speeds. During friction stirring amorphous silica powder was placed into a groove made in the joining line of Al 1100 plates. Friction stirringwas performed with clockwise tool rotational speeds of 600 rpm, 865 rpm, 1140 rpm or 1500 rpm with a constant 45 mm/min travelling speed and a 2° tilt angle. High rotational speed (1140 rpm) facilitated material flow in the stir zone, contributing to fine aluminum matrix grain size (30- 10μm) as a result of dynamic recrystallization. Stirring at this rotational speed also caused the fracturingrelated refinement of silica particles to 10μm particle sizethat isassociated with good distribution in the aluminum matrix. Reduction in wear rate of friction stir processed Al1100 with improved hardness was believed to be due to the presence of hard silicawith high interfacial strength and high hardness of recrystallized aluminum grains in the stir zone.

Enhancing Properties of Deproteinized Natural Rubber with Rice Husk Ash Silica for Use as a Dental Material

Rice husk is an agricultural residue from a rice-mill known as a rich source of silica. In this study, the rice husk was extracted for the contained silica by pretreatment with hydrochloric and calcination at 700 °C, and the white rice husk ash (WRA) mainly consisting of the silica was finally obtained. WRA was then investigated for its composition and structure with X-ray fluorescence (XRF) and X-ray diffractometer (XRD). The results showed that WRA contained a large amount of silica (90%) with amorphous structure. After that, WRA was used as filler for the preparation of natural rubber products. Two kinds of the natural rubber products were prepared here: 1) the pure natural rubber (PNR) product and 2) the deproteinized natural rubber (DNR) product. DNR was a protein removal natural rubber which is suitable for use as a dental material with the low allergenic properties caused from the proteins. Additionally, DNR used in this study could be provided by removing proteins from the natural rubber latex with 0.1 % urea in the presence of surfactant at room temperature. It was found that the nitrogen content (main element of proteins) of DNR was lower than PNR under the test condition. For the preparation of natural rubber products, WRA was mixed into the PNR and DNR latexes comparing with the commercial silica (Hisil-233). All finished latexes were compounded to obtain the natural rubber products. The viscoelastic properties and the cure characteristics of the entire products were investigated. It can be observed that WRA can be comparable with the commercial silica for use as filler for the natural rubber products. This is an attractive option to produce dental materials from the agricultural residues, which will reduce the cost of the production and also add value to the agricultural residues.

Novel Synthesis of Nay Zeolite from Rice Husk Silica: Modification with Zno and Zns for Antibacterial Application

Zeolite Y in the sodium form (NaY) was synthesized using amorphous silica ash derived from waste rice husks under hydrothermal conditions. Structural characterization of NaY before and after modification with ZnO and ZnS has been done using powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 adsorption-desorption at -196 °C, scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The effects of the Na2O/SiO2 and Si/Al ratios, aging temperature and crystallization time on the optimized synthesis of NaY were thoroughly investigated. Thus the regulated Na+ impurity concentration in the starting hydrogel was found to act as a template-assisted synthesis of zeolite NaY by the potential incorporation of Al atoms into the zeolite framework. Results of surface analyses indicate that the interactions of ZnO and ZnS with NaY zeolite are distinguishable and thus the higher interaction is observed for the latter. While ZnII has experienced electrostatic bonding interaction with the framework oxygen atoms, creation of mesopores in NaY due to local destruction of the zeolite lattice around the growing ZnS particles was evidenced. Wonderfully, ZnS/NaY exhibited a high performance in prohibiting the growth of Escherichia coli (E. coli) and negligible from P. Aeruginosa, and these important features make it a potential candidate as an antimicrobial agent for controlling implant-related infections.

Effect of internal alkali activation on pozzolanic reaction of low-calcium fly ash cement paste

Fly ash is often added to concrete as a filler and to improve strength and durability. The pozzolanic reaction between the silica and alumina in low-calcium fly ash and the Ca(OH)2 from hydrated cement proceeds slowly after an initial rapid reaction so unreacted fly ash particles remain in the paste even after aging. This limits the improvement in the strength of the concrete and it is therefore necessary to accelerate the pozzolanic reaction of low-calcium fly ash cement paste to maximize strength and durability. The present study suggested an internal alkali activation at late age (i.e. at 3 months), considering that an alkali activation can affect the cement hydration adversely at the early age (i.e. at 1 month). In the experimental study, the effects on the pozzolanic reaction of a saturated Ca(OH)2 activation applied 3 months after casting were investigated, as indicated by Ca(OH)2 content, pore size distribution and microstructure of cement paste with 40 mass% replacement with low-calcium fly ash and a water to binder ratio of 0.30. This was compared with water injection, and with untreated control samples. Water injection into fly ash cement paste 3 months after casting increased the Ca(OH)2 content after the injection for 1 and 3 months, but decreased the Ca(OH)2 content slightly in fly ash cement paste after the injection for 7 and 9 months. Meanwhile, saturated Ca(OH)2 solution injected 3 months after casting slightly decreased the Ca(OH)2 content in fly ash cement paste after the activation for 1 month and later, and reduced both total pore volume and macropore volume. As a result, internal alkali activation was more effective in accelerating the pozzolanic reaction of low-calcium fly ash cement paste than water injection. These findings were supported by the observation of differences in the microstructure between the untreated control sample and the sample applying alkali or water injection.

Chitosan Membrane with Blending of Rice Hull Ash Silica and Polyethylene Glycol for Cu(II) Adsorption in Aqueous Solution

In this research, polyethylene glycol (PEG) and rice hull ash silica were blended to modify chitosan membrane to improve the adsorption capability of copper ion. Scanning electron microscopy (SEM) and water affinity were performed to characterize membranes. Batch adsorption experiments were conducted with various contact time and Cu (II) concentrations to evaluate the adsorption kinetics and thermodynamics. Results show that adsorption fitted to Langmuir model and followed a kinetic model of pseudo-second-order.